dmaengine: PL08x: re-jig the starting of txds

Rather than code the de-queue of the txd several times, move that into
the start_txd function.  Rename this to better illustrate what it's
now doing, and call this function when starting a delayed memcpy().

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 88661fa..c278d23 100644 (file)
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -354,20 +354,25 @@ static int pl08x_phy_channel_busy(struct pl08x_phy_chan *ch)
  * been set when the LLIs were constructed.  Poke them into the hardware
  * and start the transfer.
  */
-static void pl08x_start_txd(struct pl08x_dma_chan *plchan,
-       struct pl08x_txd *txd)
+static void pl08x_start_next_txd(struct pl08x_dma_chan *plchan)
 {
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_phy_chan *phychan = plchan->phychan;
-       struct pl08x_lli *lli = &txd->llis_va[0];
+       struct pl08x_lli *lli;
+       struct pl08x_txd *txd;
        u32 val;
 
+       txd = list_first_entry(&plchan->pend_list, struct pl08x_txd, node);
+       list_del(&txd->node);
+
        plchan->at = txd;
 
        /* Wait for channel inactive */
        while (pl08x_phy_channel_busy(phychan))
                cpu_relax();
 
+       lli = &txd->llis_va[0];
+
        dev_vdbg(&pl08x->adev->dev,
                "WRITE channel %d: csrc=0x%08x, cdst=0x%08x, "
                "clli=0x%08x, cctl=0x%08x, ccfg=0x%08x\n",
@@ -1272,15 +1277,8 @@ static void pl08x_issue_pending(struct dma_chan *chan)
 
        /* Take the first element in the queue and execute it */
        if (!list_empty(&plchan->pend_list)) {
-               struct pl08x_txd *next;
-
-               next = list_first_entry(&plchan->pend_list,
-                                       struct pl08x_txd,
-                                       node);
-               list_del(&next->node);
                plchan->state = PL08X_CHAN_RUNNING;
-
-               pl08x_start_txd(plchan, next);
+               pl08x_start_next_txd(plchan);
        }
 
        spin_unlock_irqrestore(&plchan->lock, flags);
@@ -1661,14 +1659,7 @@ static void pl08x_tasklet(unsigned long data)
 
        /* If a new descriptor is queued, set it up plchan->at is NULL here */
        if (!list_empty(&plchan->pend_list)) {
-               struct pl08x_txd *next;
-
-               next = list_first_entry(&plchan->pend_list,
-                                       struct pl08x_txd,
-                                       node);
-               list_del(&next->node);
-
-               pl08x_start_txd(plchan, next);
+               pl08x_start_next_txd(plchan);
        } else if (plchan->phychan_hold) {
                /*
                 * This channel is still in use - we have a new txd being
@@ -1700,7 +1691,13 @@ static void pl08x_tasklet(unsigned long data)
                                BUG_ON(ret);
                                waiting->phychan_hold--;
                                waiting->state = PL08X_CHAN_RUNNING;
-                               pl08x_issue_pending(&waiting->chan);
+                               /*
+                                * Eww.  We know this isn't going to deadlock
+                                * but lockdep probably doens't.
+                                */
+                               spin_lock(&waiting->lock);
+                               pl08x_start_next_txd(waiting);
+                               spin_unlock(&waiting->lock);
                                break;
                        }
                }